Foreign students are persons admitted by a country other than their own, usually under special permits or visas, for the specific purpose of following a particular course of study in an accredited institution of the receiving country.

Context:

Foreign students are students who do not hold the citizenship of the country for which the data are collected. While pragmatic and operational, this classification may give rise to inconsistencies resulting from national policies regarding naturalisation of immigrants, combined with the inability of several countries to report separately foreign students net of those holding permanent residence permits.

As a result, countries where naturalisation of immigrants is stringent and identification of non-resident foreign students impossible over-estimate the size of the foreign student body, compared to countries granting citizenship to their immigrants more easily.(Education at a Glance, OECD, Paris, 2002, Glossary).

Source
Publication:

Recommendations on Statistics of International Migration, Revision 1, Statistical Papers, Series M, No. 58, United Nations, New York, 1998, Glossary.